The invention is concerned with a new basting stitch mechanism for a sewing machine; more specifically, with such a mechanism wherein the sewing needle is retracted from cooperation with a sewing machine loop taker in order to prevent stitch formation.
There are, in the prior art, examples of needle bars for sewing machines which react to the event of striking of an impenetrable object by collapse of the needle bar in order to avoid hazard to the operator or damage to the sewing machine or the work material. Such devices are shown in the U.S. Pat. Nos. 3,799,090 of Sheroff, 3,575,121 of Berube, and 3,471,325 of Berube. In some of the above devices, normal operation of the needle bar is effected automatically, while in others, the needle bar must be manually reset.
There is also in the prior art the U.S. Pat. No. 2,871,810 of Quitter, which discloses a multiple needle sewing machine utilizing a very complicated hollow needle bar arrangement which will permit a needle bar to be withdrawn from operation.
Further, U.S. Pat. No. 3,507,236 of Komuro, discloses an arrangement in a needle bar using screw threads permitting the needle bar to be shortened to interfere with stitch formation. This device requires cessation of operation in order to stop subsequent stitch formation, or in order to reinitiate stitch formation by the sewing needle.
What is required is a device having a selectively retractable needle mechanism which is simple of construction and reliable of operation, and susceptable of automatic disengagement and reengagement in order to effect selective basting.